Apparatus and methods for intravenous gas elimination

ABSTRACT

A gas elimination apparatus and a method for use in an intravenous delivery system are provided. The apparatus includes a fluid inlet coupling a fluid flow into a liquid chamber, a fluid outlet protruding into the liquid chamber, and a flow diversion member proximal to the fluid outlet. The flow diversion member configured to block a direct flow between the fluid inlet and the fluid outlet. The apparatus includes a membrane separating a portion of the liquid chamber from an outer chamber and a gas venting valve fluidically coupling the outer chamber with the atmosphere. The flow diversion member may be mechanically supported by at least one strut or elongate member extending along a flow direction into the liquid chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a continuation of U.S. patent application Ser. No.15/167,914, filed May 27, 2016, entitled “APPARATUS AND METHODS FORINTRAVENOUS GAS ELIMINATION,” which is a continuation in part of, U.S.patent application Ser. No. 14/723,415, filed May 27, 2015, entitled“APPARATUS AND METHODS FOR INTRAVENOUS GAS ELIMINATION,” the contents ofwhich are herein incorporated by reference in their entirety, for allpurposes.

BACKGROUND

The present disclosure is generally related to apparatus and methods forgas elimination in intravenous (IV) delivery systems. More specifically,the present disclosure relates to an apparatus for gas elimination in IVdelivery that is independent of the orientation of a fluid line in theIV delivery system.

Many approaches to gas elimination for IV delivery systems includebubble traps making use of the buoyancy of gas bubbles immersed in aliquid. Gas bubbles move up in a liquid container under the influence ofgravity, thereby separating gas from liquid. Other approaches to bubbletraps include a hydrophilic (i.e., water attractive) membrane to allowliquids to pass through but air to remain trapped on the other side ofthe membrane.

SUMMARY

Bubble traps based on buoyancy have the drawback that gas accumulates atthe top of the bubble trap due to the gas/liquid density difference andneeds to be manually removed by a clinician, thus distracting resourcesfrom surgery or therapy and adding the risk of human error, neglect orforgetfulness. Additionally, the orientation of buoyancy-based devicesneeds to be fixed in space relative to gravity to direct the bubbles toa specified location. When the orientation is not fixed correctly,bubbles may remain in the liquid and can be introduced to the patient.Membrane-based bubble traps which employ a hydrophilic membrane, on theother hand, are not suitable to work with blood products. In fact, thehydrophilic property of the membrane (e.g., pore sizes) can lead toclogging of the membrane by blood cells or blood clots, ultimatelyblocking the fluid flow altogether.

More generally, some bubble traps do not remove enough bubbles, or aretoo easily overcome by larger boluses of air, at the flow rates that arecommon for intravenous (IV) therapy. Accordingly, there is a need for animproved bubble trap or air elimination device which can efficientlyremove a wide range of bubble sizes across a wide range of flows for IVfluids including blood products, independent of orientation, and withautomatic venting of the gases/air into the atmosphere.

In some embodiments, a gas elimination apparatus for use in anintravenous (IV) delivery system includes a fluid inlet coupling a fluidflow into a liquid chamber. The apparatus also includes a fluid outletprotruding into the liquid chamber and a flow diversion member proximalto the fluid outlet, the flow diversion member configured to block adirect flow between the fluid inlet and the fluid outlet. Moreover, theapparatus may include a membrane separating a portion of the liquidchamber from an outer chamber, and a gas venting valve fluidicallycoupling the outer chamber with the atmosphere. In some embodiments, theflow diversion member is mechanically supported by at least one strut orelongate member extending along a flow direction into the liquidchamber.

In further embodiments, intravenous (IV) delivery systems include acontainer including an intravenous liquid, a mechanism to provide apressure to move the intravenous liquid through a fluid line to apatient, a fluid line, and a gas elimination apparatus fluidicallycoupled with the fluid line and configured to remove gas bubbles fromthe intravenous liquid. The gas elimination apparatus includes a flowdiversion member configured to block a direct flow between a fluid inletand a fluid outlet, the flow diversion member supported by at least onestrut or elongate member extending from the fluid outlet to the flowdiversion member. The gas elimination apparatus also includes a membraneseparating a portion of the fluid chamber from an outer chamber, and agas venting valve fluidically coupling the outer chamber and theatmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an intravenous delivery system, according to someembodiments.

FIG. 2A illustrates a gas elimination apparatus for use in anintravenous system, according to some embodiments.

FIG. 2B illustrates a detail of a gas elimination apparatus for use inan intravenous system, according to some embodiments.

FIGS. 2C-F illustrate cross sectional views of a flow diversion memberin a gas elimination apparatus for use in an intravenous system,according to some embodiments.

FIGS. 2G-H illustrate front views of a flow diversion member and thestruts connecting the flow diversion member to a wall of a gaselimination apparatus for use in an intravenous system, according tosome embodiments.

FIG. 3A illustrates a cross-sectional view of a gas eliminationapparatus for use in an IV delivery system, according to someembodiments.

FIG. 3B illustrates a longitudinal and a sagittal cross-sectional viewof a gas elimination apparatus for use in an IV delivery system,according to some embodiments.

FIG. 3C illustrates a longitudinal and a sagittal cross-sectional viewof a gas elimination apparatus for use in an IV delivery system,according to some embodiments.

FIG. 4A illustrates a perspective of a gas elimination apparatus for usein an IV delivery system, according to some embodiments.

FIG. 4B illustrates a center hub for a gas elimination apparatus for usein an IV delivery system, according to some embodiments.

FIG. 4C illustrates a detail of a gas elimination apparatus for use inan IV delivery system, according to some embodiments.

FIG. 5 illustrates a flowchart in a method for delivering a fluidmedication with an IV delivery system, according to some embodiments.

FIG. 6A illustrates a perspective of a gas elimination apparatus for usein an IV delivery system, according to some embodiments.

FIG. 6B illustrates a cross-section of a gas elimination apparatus foruse in an IV delivery system, according to some embodiments.

FIG. 6C illustrates a cross-section of a gas elimination apparatus foruse in an IV delivery system, according to some embodiments.

FIG. 6D illustrates a cross-section of a gas elimination apparatus foruse in an IV delivery system, according to some embodiments.

FIG. 7A illustrates a support cage including a membrane, according tosome embodiments.

FIG. 7B illustrates the support cage of FIG. 7A including a flowdiversion member cutout, according to some embodiments.

FIG. 7C illustrates a cross-section of a gas elimination apparatus witha flow diversion member, according to some embodiments.

FIG. 7D illustrates a perspective of a flow diversion member used in agas elimination apparatus, according to some embodiments.

FIG. 7E illustrates a side view of the flow diversion member of FIG. 7D,according to some embodiments.

FIG. 8A illustrates a support cage of a gas elimination apparatus,including a flow diversion member cutout, according to some embodiments.

FIG. 8B illustrates a cross-section of a gas elimination apparatus witha flow diversion member, according to some embodiments.

FIG. 8C illustrates a perspective of a flow diversion member used in agas elimination apparatus, according to some embodiments.

FIG. 8D illustrates a side view of the flow diversion member of FIG. 8C,according to some embodiments.

FIG. 9A illustrates a perspective of a support cage for a gaselimination apparatus including a flow diversion member cutout,according to some embodiments.

FIG. 9B illustrates a top view of the flow diversion member of FIG. 9A,according to some embodiments.

FIG. 9C illustrates a side view of the flow diversion member of FIG. 9A,according to some embodiments.

FIG. 10A illustrates a side view of a support cage for a gas eliminationapparatus including a flow diversion member cutout, according to someembodiments.

FIG. 10B illustrates a top view of the flow diversion member of FIG.10A, according to some embodiments.

FIG. 10C illustrates a side view of the flow diversion member of FIG.10A, according to some embodiments.

FIG. 11 illustrates a gas venting valve for use in a gas eliminationapparatus, according to some embodiments.

In the figures, elements having the same or similar reference numeralhave the same or similar functionality or configuration, unlessexpressly stated otherwise.

DETAILED DESCRIPTION

During IV delivery of liquids (e.g., crystalloids, colloids, bloodproducts, drugs) to patients, a risk exists wherein gas bubbles or gasboluses may be inadvertently delivered into the body through thedelivery system. Because the amount of air that can be tolerated by anindividual patient may vary or be uncertain, caregivers make everyeffort to remove all gases and even small gas bubbles during the setup(priming) of the delivery system. Unfortunate errors can occur duringthis process, leaving some air/gas remaining in the delivery lines whichshould ideally be removed. Furthermore, once a system is primed, thereexist additional mechanisms for air/gas to be introduced into the tubingleading to the patient. These mechanisms include hanging of new IV bags,introduction of bolus injections through access ports, and warming ofthe IV fluid, which inherently leads to out-gassing. The latter occursbecause the solubility of a gas in a liquid is dependent upontemperature. IV bags are typically introduced either near freezingtemperatures (e.g., blood products) or at room temperature (e.g., mostother fluids like colloids and crystalloids). When these fluids arewarmed from freezing or room temperature up to a higher temperature nearbody temperature (e.g., 37-41.degree. C.), gases come out of the liquidin the form of bubbles which are desirably removed to avoid deliveringthem to the patient. In most disposable IV sets, this is achieved usinga bubble “trap” of some sort.

The present disclosure includes a gas elimination device, which isorientation independent, works with many IV fluids including bloodproducts, and automatically vents trapped gases to the ambientenvironment. Embodiments of a gas elimination apparatus as disclosedherein may advantageously be placed just downstream of a fluid warmingdevice where bubbles are formed by out-gassing, or may be placed atother locations in an IV delivery system to remove air/gas. The presentdisclosure may include additional features such as the ability to stopflow using a valve (e.g., stopcock) and/or the ability to introducebolus drug injections on the upstream side to allow clinicians peace ofmind that any air/gas they inadvertently introduce during an injectioninto the system will be removed prior to the liquid reaching thepatient.

Gas elimination devices for use in intravenous delivery systems asdisclosed herein may use the lower density of gases versus liquids toallow bubbles to migrate to a region where they can be automaticallyremoved, and some embodiments employ membranes exploiting differencesbetween how gases and liquids interact with surfaces of a given energystate. For example, some embodiments employ a hydrophobic (i.e., wateraverse) membrane to allow air/gas to escape into a room atmosphere, butliquid to remain in the system.

FIG. 1 illustrates an IV delivery system according to some embodiments.The IV delivery system includes a frame 140 supporting a container 143having an intravenous liquid 150. In some embodiments, intravenousliquid 150 includes a gas that may be dissolved, may be in the form ofgas bubbles 151, may form a gas phase above a liquid surface, orcomprise any combination of these forms. Gas in gas bubbles 151 may beair, nitrogen, oxygen, or any other gas susceptible of being dissolvedin intravenous liquid 150. Intravenous liquid 150 may be any liquidsuitable for intravenous delivery. Common intravenous liquids includecrystalloids (e.g., saline, Lactated Ringers, glucose, dextrose),colloids (e.g., hydroxyethyl starch, gelatin), liquid medications,buffer solutions, and blood products (e.g., packed red blood cells,plasma, clotting factors) or blood substitutes (e.g., artificial blood)that are desired to be injected intravenously to a patient 160. A fluidline 130 carries intravenous liquid 150 from container 143 to patient160. In some embodiments, intravenous liquid 150 moves through fluidline 130 by a pressure differential created by gravity. Accordingly, insome embodiments container 143 is disposed on frame 140 at a higherelevation relative to the patient. In some embodiments, a pump 145creates the pressure differential to move liquid 150 through fluid line130.

Some embodiments of an IV delivery system consistent with the presentdisclosure include a thermostat 147 to adjust a temperature ofintravenous liquid 150 in container 143. The IV delivery system includesa gas elimination apparatus 100 fluidically coupled with fluid line 130.Gas elimination apparatus 100 is configured to remove gas bubbles 151from liquid 150. In some embodiments, gas elimination apparatus 100 isconfigured to automatically remove gas bubbles 151 from intravenousliquid 150 with minimal intervention from a healthcare professional.Further, according to some embodiments, gas elimination apparatus 100 isconfigured to remove gas bubbles 151 from liquid 150 regardless of itsorientation relative to gravity. In some embodiments, gas bubbles 151are removed from intravenous liquid 150 in fluid line 130 and releasedto the room at atmospheric pressure P.

In some embodiments, the operation of an IV delivery system as depictedin FIG. 1 may be controlled wirelessly by a remote controller 170located, for example, at a nurse station. The wireless communication maybe performed by an antenna 175 on the controller side and an antenna 155on frame 140. Controller 170 includes a processor 171 and a memory 172.Memory 172 may include commands and instructions, which when executed byprocessor 171, cause controller 170 to perform at least partially someof the steps included in methods consistent with the present disclosure.Further according to some embodiments, a first bubble sensor 181 may beplaced upstream from gas elimination apparatus 100, and a second bubblesensor 182 may be placed downstream from gas elimination apparatus 100.Bubble sensors 181 and 182 may include any type of sensing devices,including optical sensors, a video camera and a laser, ultrasoundsensors or other electrical types of sensing devices, such as acapacitance measuring circuit, or the like. In that regard, at least oneof bubble sensors 181 and 182 may provide information about a number ofbubbles per cross-sectional area, per unit time, flowing through fluidline 130, and their approximate diameter. Furthermore, bubble sensors181 and 182 may wirelessly communicate with antenna 155 and withcontroller 170, to receive instructions from and provide data to,controller 170.

Controller 170, antenna 155, and bubble sensors 181 and 182 maycommunicate via a Bluetooth, Wi-Fi, or any other radio-frequencyprotocol. Accordingly, controller 170 may be configured to process areading from bubble sensors 181 and 182 and determine a bubbleelimination rate for gas elimination apparatus 100. Based on the bubbleelimination rate, controller 170 may provide commands to pump 145 andother devices within frame 140 to increase the bubble elimination rate.Furthermore, controller 170 may provide an alarm to a centralized systemwhen a bubble count in sensor 182 becomes higher than a first threshold,or when the bubble elimination rate becomes lower than a secondthreshold. In some embodiments, controller 170 may also provide commandsto thermostat 147 to regulate the temperature of intravenous liquid 150based on the bubble counts provided by at least one of sensors 181 and182. A valve 190 in fluid line 130 may be operated to allow intravenousliquid 150 to flow into patient 160 when bubble sensor 182 detects abubble content lower than a predetermined threshold. In someembodiments, valve 190 may be closed by controller 170 when an alarm isissued as described above.

FIG. 2A illustrates a gas elimination apparatus 200 for use in anintravenous system, according to some embodiments. Gas eliminationapparatus 200 includes a fluid inlet 201 coupling a fluid flow into aliquid chamber 202. A fluid outlet 203 protrudes into liquid chamber 202to collect and deliver the bubble-free fluid to fluid line 130, which iscoupled to apparatus 200 through a connector 217. A flow diversionmember 205 proximal to fluid outlet 203 is configured to block a directfluid flow between fluid inlet 201 and fluid outlet 203. Accordingly,the fluid flow that is transferred out through fluid outlet 203 hasspent some time in liquid chamber 202 before exiting, allowing bubbles151 to migrate to an outer chamber 220 through a first membrane 210 anda second membrane 211. A wall 215 provides support to membranes 210 and211, and also to flow diversion member 205. In some embodiments, asupport cage 213 may provide further structural support to membranes 210and 211. This may be especially beneficial when membranes 210 and 211include a sheet membrane, which may be flexible or soft. Membranes 210and 211 cover a portion of the interior surface of liquid chamber 202,and separate liquid chamber 202 from outer chamber 220. Accordingly,when intravenous liquid 150 comes in contact with membranes 210 and 211,gas bubbles 151 contained in the fluid are allowed to pass through themembrane pores, while water and other solvents or elements inintravenous liquid 150 are contained by membranes 210 and 211 withininterior chamber 202.

Gas elimination apparatus 200 includes a gas venting valve 225fluidically coupling outer chamber 220 with the atmosphere. Outerchamber 220 is fluidically coupled with valve chamber 221. A conduit 223transports gas from gas bubbles 151 going through membrane 211 to valvechamber 221. Accordingly, when outer chamber 220 is filled with air orgas from bubbles 151, pressure inside outer chamber 220 builds up untilvalve 225 is opened and the gas flows out into the atmosphere. Outerchamber 220 and membranes 210 and 211 may be transparent orsemi-transparent, thus allowing at least a partial view of the interiorto a healthcare professional. Alternatively, outer chamber 220 andmembranes 210 and 211 may be opaque. Membranes 210 and 211 may be formedof polymeric materials such as polytetrafluoroethylene (PTFE), and mayhave a pore size which ranges from 0.1 to a few microns (10.sup.-6 m).The thickness of membranes 210 and 211 may be in the range of 100-200microns. In some embodiments, the water breakthrough pressure may beapproximately 2-3 bar. The gas flow venting capability of membranes 210and 211 is preferably in the range of 400-700 milliliters per minute,per square cm (ml/min/cm.sup.2) but may be higher or lower. Membranes210 and 211 may comprise thin, flexible, compliant forms or may be solidor semi-solid, rigid forms. Similarly, membranes 210 and 211 may takethe form of sheets or may be formed into specific self-supporting shapesin a manufacturing step. It should be understood however, that anymembrane with appropriately hydrophobic properties may be used,consistent with the scope of the disclosure.

More specifically, membranes 210 and 211 may include a hydrophobicmembrane (“water averting”). In some embodiments, membranes 210 and 211may include a hemophobic (“blood averting”) membrane, an oleophobic(“oil averting”) membrane, or any combination of the above. Accordingly,membranes 210 and 211 may be used with any IV fluids and may beresistant to wetting with both high and low surface tension fluids aswell as blood and blood products. In some embodiments, membranes 210 and211 are constructed of polyvinylidene fluoride (PVDF) and are capable ofpassing air or other gases in both directions.

The form factor of gas elimination apparatus 200 allows it to eliminategas bubbles 151 from intravenous liquid 150 in any orientation relativeto gravity. In some embodiments, liquid chamber 202 is a cylindricalchamber having a longitudinal axis 250. Membranes 210 and 211 form thewall, ceiling, and floor of liquid chamber 202. As gas bubbles 151 orgas ‘slugs’ enter liquid chamber 202, they encounter at least one ofmembranes 210 and 211 before ever entering fluid outlet 203, regardlessof the orientation of axis 250 relative to gravity. For example, whenthe device is oriented with longitudinal axis 250 perpendicular to thedirection of gravity (horizontal, cf. FIG. 1), gas bubbles 151 rise tothe apex of the circular cross section of the cylinder, reachingmembrane 210 and filtering through to outer chamber 220. When the deviceis oriented with longitudinal axis 250 parallel to the direction ofgravity (vertical, cf. FIG. 1), gas bubbles 151 rise to the ceiling orfloor to encounter membrane 211. When bubbles or gases reach membranes210 and 211, they transit through from interior chamber 202 into outerchamber 220. In some embodiments, outer chamber 220 preventsintroduction of gases back into intravenous liquid 150 from the ambient,which can occur when the partial pressure differential across themembrane is directed towards interior chamber 202. As such, gases thatare removed from interior chamber 202 into outer chamber 220 areautomatically vented through the one or more valves 225 or additionalmembranes (e.g., umbrella type). In some embodiments, valves 225 may beone-way operating valves that allow gases to escape into the atmospherebut not to enter back into gas elimination apparatus 200.

Dimensions of gas elimination apparatus 200 in embodiments consistentwith the present disclosure allow gas bubbles 151 of expected sizesgreater than a minimum value to reach membranes 210 and 211 in less thanthe transit time it takes intravenous liquid 150 to travel from fluidinlet 201 to fluid outlet 203. For example, the length of the liquidchamber 202 may be approximately 30 mm (along longitudinal axis 250) andthe diameter of internal chamber 202 may be approximately 20 mm. Withsuch dimensions, sub-microliter bubbles (<1 mm in diameter) may betransferred to outer chamber 220 before traversing the length of liquidchamber 202 due to their buoyancy. In some embodiments, the length ofliquid chamber 202 may be up to 50 mm, or more, while the diameter ofliquid chamber 202 may be somewhere between 10 mm to 20 mmm as desired.

Additional non-cylindrical shapes of liquid chamber 202 may beconsistent with an orientation-independent gas elimination apparatus asdisclosed herein. For example, triangular, rectangular, pentagonal,hexagonal, heptagonal, octagonal, and higher face-number shaped liquidchambers may perform similarly. The cylindrical shape of liquid chamber202 is well suited for fabrication and handling due to its symmetric,continuous nature.

FIG. 2B illustrates a detail of gas elimination apparatus 200, accordingto some embodiments. Gas bubbles 151 transit through membrane 210 andfrom outer chamber 220 into valve chamber 221. Also, some gas bubbles151 transit through membrane 211 and conduit 223 into valve chamber 221.Accordingly, gas bubbles 151 build up a pressure inside valve chamber221 such that eventually the pressure becomes about the same as orsomewhat greater than room pressure P (cf. FIG. 1). At this point, valve225 automatically opens, releasing the excess pressure in the form ofthe gas inside gas bubbles 151.

FIGS. 2C-F illustrate cross sectional views of flow diversion members205C-F in gas elimination apparatus 200 for use in an intravenoussystem, according to some embodiments. Flow diversion members 205C-Fprevent or restrict bubbles 151 from traveling in straight linesdirectly from fluid inlet 201 to fluid outlet 203. This may be desirableduring operation in an orientation where longitudinal axis 250 isparallel to the direction of gravity (vertical, cf. FIG. 1), however,even during operation where longitudinal axis 250 is perpendicular tothe direction of gravity (horizontal, cf. FIG. 1), diversion members205C-F induce bubbles 151 to substantially follow the plurality of flowstreamlines 231 along a curved path from fluid inlet 201 to fluid outlet203. Flow diversion members 205C-F force bubbles 151 or gas slugs tomigrate (i.e. through diverted flow streamlines 231 and buoyancy)towards membranes 210 and 211 prior to any chance to make multiple turnsand reach fluid outlet 203. Flow diversion members 205C-F substantiallyor completely block fluid outlet 203 when viewed from fluid inlet 201along axis 250. In some embodiments, flow diversion members 205C-F allowa blood component other than a gas bubble to reach fluid outlet 203, andthereby stay in the flow stream. For example, a blood component asdisclosed herein may include any one of a red blood cell, or anyundissolved solid in the blood stream. Accordingly, flow streamlines 231emanating from fluid inlet 201 reach fluid outlet 203 along a path thatdeviates from a straight line path. Flow diversion members 205C-F maypresent a hydrodynamic form factor to the flow of the intravenous liquid150 or may present a non-hydrodynamic form factor such as a stagnationplane. In embodiments consistent with the present disclosure, thesurface of flow diversion members 205C-F presented to the incoming flowof intravenous liquid 150 (the right hand side of flow diversion members205C-F in FIGS. 2C-F) may be spherical or dome shaped to smoothly divertthe liquid flow outwards and away from fluid outlet 203. Examples ofnon-spherical or semi-spherical (i.e., having one or more featuressimilar to a sphere) shapes of flow diversion member 205 consistent withthe gas elimination apparatus as disclosed herein include flow diversionmember 205C with ellipsoidal shape, flow diversion member 205D with amushroom or umbrella shape, or pyramidal shapes. FIG. 2E illustratesflow diversion member 205E that is conical, and FIG. 2F illustrates flowdiversion member 205F with a pyramidal shape. One of ordinary skill willrecognize that the shape of flow diversion member 205 may be any desiredshape, such as a disc, or the like. Additionally, the expanse(cross-sectional area with respect to axis 205) of flow diversion member205 may beneficially extend beyond the diameter of fluid outlet 203 toforce bubbles 151 further away from the outlet and direct them closer tomembranes 210 and 211 (e.g., flow diversion members 205D-F).

FIGS. 2G-H illustrate front views of flow diversion members 205G-H andstruts 230 connecting flow diversion member 205G-H to wall 215 of gaselimination apparatus 200 according to some embodiments. Struts 230 inflow diversion members 205G-H may have hydrodynamic shapes to avoidadditional pressure loss to the liquid as it passes through gaselimination apparatus 200. For example, struts 230 may be thinhydrofoils presenting a low and smooth angle of attack to the incomingfluid. As illustrated in FIGS. 2G-H, struts 230 may be attached to wall215 through supports 235. In some embodiments, the material for flowdiversion members 205G-H, struts 230, and supports 235 may be the sameas the material for support cage 213 and wall 215 in gas eliminationapparatus 200.

FIG. 3A illustrates a cross-sectional view of gas elimination apparatus200A for use in an IV delivery system, according to some embodiments.The cross-sectional view illustrated in FIG. 3A is taken along segmentA-A′ in FIG. 2A. Gas elimination apparatus 200A includes wall 315Ahaving protrusions 313A contacting wall 215, thus providing structuralsupport to membrane 210 and to outer chamber 320A. Protrusions 313A areformed from wall 315A and may contact membrane 210 at points alternatingwith features of support cage 213. Accordingly, protrusions 313A may beparallel to longitudinal axis 250. Outer chamber 320A is analogous toouter chamber 220 (cf. FIG. 2A). Accordingly, the risk of collapse whenthere is low gas pressure in outer chamber 320A is substantiallyreduced.

FIG. 3B illustrates a longitudinal and a sagittal cross-sectional viewof gas elimination apparatus 200B for use in an IV delivery system,according to some embodiments. The sagittal cross-sectional view in FIG.3B corresponds to segment B-B′ in the longitudinal cross-sectional view.Gas elimination apparatus 200B includes wall 315B having protrusions313B contacting membrane 210 and providing structural support to outerchamber 320B. Support cage 213 supports membrane 210 as illustrated ingas elimination apparatus 200A. Outer chamber 320B is analogous to outerchamber 220 (cf. FIG. 2A). In some embodiments, protrusions 313B areperpendicular to longitudinal axis 250.

In some embodiments, protrusions 313B include depressions 323intersecting the protrusions to provide a flow continuity to outerchamber 320B.

FIG. 3C illustrates a longitudinal and a sagittal cross-sectional viewof gas elimination apparatus 200C for use in an IV delivery system,according to some embodiments. Gas elimination apparatus 200C includes arigid membrane 310 having protrusions 313C forming outer chamber 320C.The sagittal cross-sectional view illustrated in FIG. 3C is taken alongsegment C-C′ of the longitudinal cross-sectional view, and showsprotrusions 313C in more detail. Protrusions 313C are formed in a planesubstantially perpendicular to axis 250 and include notches 314 or gapsto allow for air/gas bubbles 151 to pass through, thereby forming afluidically connected outer chamber 320C.

FIG. 4A illustrates a perspective of a gas elimination apparatus 400 foruse in an IV delivery system, according to some embodiments. Gaselimination apparatus 400 comprises a fluid inlet 401 coupling a fluidflow into a liquid conduit 430. Liquid conduit 430 is concentric with ahollow chamber 421 along a longitudinal axis 450, wherein hollow chamber421 is separated from liquid conduit 430 by a membrane 410. Gaselimination apparatus 400 also includes a fluid outlet 403 fluidicallycoupled with liquid conduit 430, an outer chamber 420 concentric withliquid conduit 430 and separated from liquid conduit 430 by a membrane410. In some embodiments, gas elimination apparatus 400 includes acenter hub 405 fluidically coupling hollow chamber 421 and outer chamber420. Further, some embodiments include gas venting valve 225 fluidicallycoupling outer chamber 420 and the atmosphere. In some embodiments, gaselimination apparatus 400 further includes supports 440 on either end ofhollow chamber 421. Supports 440 block or restrict the liquid flowthrough hollow chamber 421, so that only or mostly gas from gas bubbles151 accumulates in hollow chamber 421.

FIG. 4B illustrates center hub 405 for gas elimination apparatus 400 foruse in an IV delivery system, according to some embodiments. Center hub405 is supported on wall 415 of outer chamber 420 through radial spokes423. Radial spokes 423 may be hollow and have a conduit 425 fluidicallycoupling hollow chamber 420 with the outer chamber.

FIG. 4C illustrates a detail of gas elimination apparatus 400 for use inan IV delivery system, according to some embodiments. Gas bubbles 151transit through membrane 410 into hollow chamber 421 and into outerchamber 420. The gas in hollow chamber 421 is transferred into outerchamber 420 through conduits 425 in spokes 423 of hub 405. Once enoughgas pressure builds up in outer chamber 420, valve 225 opensautomatically, releasing the gas in gas bubbles 151 into the atmosphere.

FIG. 5 illustrates a flowchart in a method 500 for delivering anintravenous liquid with an intravenous system, according to someembodiments. Methods consistent with method 500 may include using a gaselimination apparatus as disclosed herein, having at least one membrane(e.g., gas elimination apparatus 100, 200, 200A-C, and 400, andmembranes 210, 211, and 410, cf. FIGS. 1, 2A-H, 3A-C and 4A,respectively). Further according to some embodiments, methods consistentwith the present disclosure may include an IV delivery system asdisclosed herein. The IV delivery system may include a frame, a fluidcontainer, a pump, a thermostat, a fluid line, an antenna, at least abubble sensor, and a valve as disclosed herein (e.g., frame 140, fluidcontainer 143, pump 145, fluid line 130, antenna 155, bubble sensors 181and 182, and valve 190, cf. FIG. 1).

Methods consistent with method 500 may include at least one step inmethod 500 performed by a controller including a memory and a processor(e.g., controller 170, processor 171, and memory 172, cf. FIG. 1). Thememory storing commands, which when executed by a processor cause thecontroller to perform at least one step in method 500. Further accordingto some embodiments, methods consistent with method 500 may include atleast one, but not all, of the steps illustrated in FIG. 5. Moreover, insome embodiments a method as disclosed herein may include steps inmethod 500 performed in a different sequence than that illustrated inFIG. 5. For example, in some embodiments at least two or more of thesteps in method 500 may be performed overlapping in time, or evensimultaneously, or quasi-simultaneously.

Step 502 includes receiving a fluid flow through the fluid inlet of thegas elimination apparatus. In some embodiments step 502 includes sendingcommands to the pump in the IV delivery system to begin delivery of theintravenous liquid through the fluid line.

Step 504 includes placing the fluid flow in contact with the membraneseparating the liquid chamber from the outer chamber in the gaselimination apparatus. Step 506 includes allowing a gas in the fluidflow to transition through the membrane into the outer chamber. Step 508includes opening the valve in the outer chamber to vent gas into theatmosphere. In some embodiments, step 508 includes automatically openingthe valve when the gas pressure in the outer chamber reaches a thresholdvalue. Step 510 includes delivering the fluid flow through the fluidoutlet of the gas elimination apparatus.

Step 512 may further include determining a gas elimination rate. In someembodiments, step 512 may include counting a number of bubbles per unitcross-sectional area per unit time along the fluid line, downstream ofthe gas elimination device using the bubble sensor. In some embodiments,step 512 further includes counting the number of bubbles per unitcross-sectional area per unit time along the fluid line, upstream of thegas elimination apparatus using another bubble sensor. In yet otherembodiments, step 512 includes measuring a bubble size and estimating atotal gas volume flow rate using data provided by the bubble sensor.

Step 514 includes adjusting a fluid flow parameter based on the gaselimination rate. In some embodiments, step 514 may include providing acommand to the pump to reduce or increase a flow rate, using thecontroller. In some embodiments, step 514 may include increasing atemperature setting of the thermostat when the gas elimination rate isgreater than a threshold value. In some embodiments, step 514 mayinclude reducing the temperature setting of the thermostat when the gaselimination rate is lower than a second threshold value. In someembodiments, step 514 includes providing an alarm to a centralizedsystem when a bubble count in sensor 182 becomes higher than a firstthreshold, or when the bubble elimination rate becomes lower than asecond threshold.

FIG. 6A illustrates a perspective of a gas elimination apparatus 600 foruse in an IV delivery system, according to some embodiments. A wall 615protects and provides structural support to the apparatus. Wall 615 mayinclude a flow indicator 627 point from a fluid inlet 601 to a fluidoutlet 603. A gas venting valve 625 allows excess gas to vent out of theapparatus from the fluid within wall 615.

In some embodiments, valve 625 may be an umbrella valve located on thecylindrical portion of the device, as shown. Some embodiments mayinclude additional umbrella valves at other locations. In someembodiments, as shown, the shape of gas elimination apparatus 600 isslightly tapered such that the circular cross-section at fluid outlet603 is larger than the circular cross-section at fluid inlet 601. Thistaper could also be reversed such that the larger end is fluid inlet 601and the smaller end is fluid outlet 603. A tapered shape may facilitatemanufacturing of the gas elimination apparatus 600.

FIGS. 6B-C illustrate a longitudinal cross-section of gas eliminationapparatus 600 including a flow diversion member 605B, C and a supportcage 613 to provide structural support to a membrane 610, according tosome embodiments. Membrane 610 may be as any water impermeable membraneas described above (e.g., membranes 210 or 211, cf. FIG. 2 and thedescription thereof). Gas elimination apparatus 600 includes liquidchamber 602, fluidly coupled with fluid inlet 601 and with fluid outlet603. Membrane 610 separates liquid chamber 602 from an outer gas chamber620. Outer gas chamber 620 is fluidly coupled to ambient through valve625, which may be a one-way valve (e.g., umbrella valve). As liquidenters gas elimination apparatus 600 through fluid inlet 601, any gasbubbles or gas volumes present in the liquid will either rise up tomembrane 610 under their own buoyancy or be deflected toward membrane610 by a flow diversion member 605B, C. When gas elimination apparatus600 is oriented with its longitudinal axis perpendicular to gravity,bubbles will rise under buoyancy or be deflected by flow diversionmember 605B or 605C and arrive at the apex of the circular cross-sectionof fluid chamber 602 to contact membrane 610. When gas eliminationapparatus 600 is oriented with its longitudinal axis parallel togravity, then bubbles will rise or be deflected to end walls 611. Oncethere, the bubbles will accumulate until they form a gas layer incontact with membrane 610, at which point they will vent to outerchamber 620. Flow diversion member 605B is spherically shaped with a cutout section facing fluid outlet 603, such that the member 605B can havea crescent or umbrella shape as shown in FIG. 2D, having a concaveinternal surface on an opposing side of the member 605B as a convexouter surface. The spherical shape is illustrated on the front end ofthe member 605B in FIG. 6B. In some embodiments, the apparatus 600 canhave a flow diversion member 605C that is half-spherically shaped, suchthat the member 605C has a mushroom shape, as depicted in FIG. 6C. Insome embodiments, the mushroom shape member 605C can also have a concaveinternal surface, similar to that shown for member 605B. In someembodiments, the mushroom shape member 605C can have a planar internalsurface.

Outer chamber 620 is annular in cross-section and is contiguous frominlet to outlet (i.e., not partitioned by ribs or protrusions). Note aswell that according to some embodiments there are no membrane surfaceson the cylinder end walls 611, which are substantially impermeable togas and liquid. Accordingly, gas venting occurs through the cylindricalmembrane, as the venting valve location is on the cylindrical section.Furthermore, in embodiments consistent with gas elimination apparatus600, flow diversion members 605B and 605C are supported by fluid outlet603, rather than by support cage 613 (see, e.g., flow diversion member205 and support cage 213, and FIGS. 2A-H).

FIG. 6D illustrates a longitudinal cross-section of gas eliminationapparatus 600 including a flow diversion member 605D, support cage 613,membrane 610, and at least two struts or elongate members 630, accordingto some embodiments. Struts or elongate members 630 may be supported byfluid inlet 601. In some embodiments, the flow would be diverted aroundthe around the flow diversion member 605D by following flow paths intoand out of the page when referencing FIG. 6D. Flow diversion member 605Dmay have any of the shapes described above (see FIGS. 2C-H and FIGS.6B-C). Generally, it is desirable that flow diversion member 605D have acutout, convex, concave, or flat portion facing fluid outlet 603, and arounded, or convex portion facing fluid inlet 601. In some embodiments,it is also desirable that struts or elongate members 630 extendgenerally along the flow direction into liquid chamber 602 to providethe least flow resistance. All other elements in FIG. 6D are asdescribed above in relation to FIGS. 6A-C and having the same referencenumerals.

FIG. 7A illustrates support cage 613 including a membrane 610, accordingto some embodiments. Membrane 610 is either attached to the interiorsurface of support cage 613 or to the exterior surface of support cage613. In some embodiments, membrane 610 may be embedded into thestructure of support cage 613. Accordingly, membrane 610 forms a barrierbetween liquid chamber 602 and outer gas chamber 620 through which onlygases may pass. Furthermore, in some embodiments, membrane 610 may bewelded or heat-bonded to support cage 613. In some embodiments, membrane610 may be insert-molded together with molding support cage 613.Accordingly, the output of the molding process for support cage 613 is awater tight cage with membrane 610 attached.

FIG. 7B illustrates support cage 613 including a cutout of flowdiversion member 705, according to some embodiments. Flow diversionmember 705, as illustrated here, is a spherical diverter and may includea cutout facing fluid outlet 603, as illustrated.

FIG. 7C illustrates a cross-section of gas elimination apparatus 600with flow diversion member 705 (see FIG. 7B), according to someembodiments. FIG. 7C presents a view of flow diversion member 705 as theflow would see it from fluid inlet 601 toward fluid outlet 603.

FIG. 7D illustrates a perspective of flow diversion member 705 used ingas elimination apparatus 600 (for example, see FIG. 6), according tosome embodiments. FIG. 7D shows a view of flow diversion member 705integrated into fluid outlet 603. Bubbles which are able to followstreamlines which approach flow diversion member 705 are directedradially out towards membrane 610 (see FIG. 7C) where they are captured,thus reducing their ability to flow into fluid outlet 603 and continueimmersed in the fluid flow downstream from gas elimination apparatus600. Flow diversion member 705 is attached to fluid outlet 603 by, forexample, two struts 730 (more or fewer struts may also be used), orelongate members, which extend out from fluid outlet 603. Accordingly,struts 730 are occluded from the fluid flow coming from fluid inlet 601by flow diversion member 705.

FIG. 7E illustrates a side view of flow diversion member 705, accordingto some embodiments. In some embodiments, and without limitation, adistance 707 from fluid outlet 603 to the far side of the cutout isapproximately 6 mm. For a perspective, in some embodiments the overallsize of gas elimination device 600 may be approximately 40-50 mm inlength, and 14-17 mm in diameter.

FIG. 8A illustrates a support cage 813 of gas elimination apparatus 600,including a flow diversion member 805, according to some embodiments.Flow diversion member 805 is spherical, being substantiallyhalf-spherical, wherein the flat-side of the half-sphere faces fluidoutlet 603. This shape is similar to other shapes described herein ashaving a mushroom shape. Bubbles which follow streamlines that bringthem to flow diversion member 805 are deflected radially out towardsmembrane 610 (not shown for clarity). The abrupt absence of diversionsurface where the sphere is cut makes it difficult for deviating bubblesto turn towards fluid outlet 603, thus increasing the likelihood oftheir capture at membrane 610.

FIG. 8B illustrates a cross-section of gas elimination apparatus 600with flow diversion member 805, according to some embodiments. FIG. 8Bpresents a view of the flow diversion member 805 as the flow would seeit moving from fluid inlet 601 toward fluid outlet 603.

FIGS. 8C-D illustrate a perspective of flow diversion 805, according tosome embodiments. FIG. 8C illustrates struts 830 coupling flow diversionmember 805 with fluid outlet 603. In some embodiments, the distance 807between the flat face of flow diversion member 805 and fluid outlet 603is approximately 1.5 mm.

FIGS. 9A-C illustrate perspective, top, and side views of support cage913 for a gas elimination apparatus 900, respectively. Support cage 913incorporates lengthwise struts to support membrane 610. In gaselimination apparatus 900, membrane 610 may be attached to the outsidesupport cage 913. Gas elimination apparatus 900 includes a flowdiversion member 905 with a cutout facing fluid outlet 903 at a distance907 of approximately 6 mm, according to some embodiments. A fluid inlet901 lets an IV fluid to flow inside a liquid chamber 902 delimited bysupport cage 913. The flow diversion member 905 can have multipleinwardly facing concave surfaces when viewed from the side (as in FIG.9C) and an umbrella-shape when viewed from the top (as in FIG. 9B).

FIG. 10A illustrates a side view of support cage 913 for a gaselimination apparatus 900 including a flow diversion member 1005 havinga semi-spherical shape, such as a mushroom, according to someembodiments.

FIGS. 10B-C illustrate top and side views of flow diversion member 1005,respectively. Accordingly, a flat side in flow diversion member 1005 maybe disposed at a distance 1007 of approximately 6 mm from fluid outlet603, according to some embodiments.

FIG. 11 illustrates a gas venting valve 1125 for use in a gaselimination apparatus 1100, according to some embodiments. Gas ventingvalve 1125 may be an umbrella valve; the surface of gas eliminationapparatus 1100 where the umbrella valve sits when in the closed positionmay be recessed or surrounded by a ridge or fence 1135 such that ifplaced in contact with another surface, the umbrella valve itself is notlimited from opening under the action of venting of internal air. Fence1135 has a height 1137 that is at least as high as the travel distanceto fully open valve 1125. Furthermore, the surface of the device wherethe umbrella valve sits when in the closed position may be recessed orsurrounded by a ridge or fence such that if placed in contact withanother surface, the umbrella valve itself is not limited from openingunder the action of venting of internal air.

The foregoing description is provided to enable a person skilled in theart to practice the various configurations described herein. While thesubject technology has been particularly described with reference to thevarious figures and configurations, it should be understood that theseare for illustration purposes only and should not be taken as limitingthe scope of the subject technology.

There may be many other ways to implement the subject technology.Various functions and elements described herein may be partitioneddifferently from those shown without departing from the scope of thesubject technology. Various modifications to these configurations willbe readily apparent to those skilled in the art, and generic principlesdefined herein may be applied to other configurations. Thus, manychanges and modifications may be made to the subject technology, by onehaving ordinary skill in the art, without departing from the scope ofthe subject technology.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

Furthermore, to the extent that the term “include,” “have,” or the likeis used in the description or the claims, such term is intended to beinclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any embodiment described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.” Theterm “some” refers to one or more. All structural and functionalequivalents to the elements of the various configurations describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and intended to be encompassed by the subject technology.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe above description.

While certain aspects and embodiments of the subject technology havebeen described, these have been presented by way of example only, andare not intended to limit the scope of the subject technology. Indeed,the novel methods and systems described herein may be embodied in avariety of other forms without departing from the spirit thereof. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thesubject technology.

It is understood that the specific order or hierarchy of steps,operations or processes disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of steps, operations or processes may berearranged. Some of the steps, operations or processes may be performedsimultaneously. Some or all of the steps, operations, or processes maybe performed automatically, without the intervention of a user. Theaccompanying method claims, if any, present elements of the varioussteps, operations or processes in a sample order, and are not meant tobe limited to the specific order or hierarchy presented.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. § 112 (f) unless the element isexpressly recited using the phrase “means for” or, in the case of amethod claim, the element is recited using the phrase “step for.”

The Title, Background, Summary, Brief Description of the Drawings andAbstract of the disclosure are hereby incorporated into the disclosureand are provided as illustrative examples of the disclosure, not asrestrictive descriptions. It is submitted with the understanding thatthey will not be used to limit the scope or meaning of the claims. Inaddition, in the Detailed Description, it can be seen that thedescription provides illustrative examples and the various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed subject matter requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed configuration or operation. The followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

The claims are not intended to be limited to the aspects describedherein, but are to be accorded the full scope consistent with thelanguage claims and to encompass all legal equivalents. Notwithstanding,none of the claims are intended to embrace subject matter that fails tosatisfy the requirement of 35 U.S.C. § 101, 102, or 103, nor should theybe interpreted in such a way.

What is claimed is:
 1. An apparatus for use in an intravenous (IV)delivery system, comprising: a fluid inlet coupling a fluid flow into aliquid chamber; a fluid outlet protruding into the liquid chamber; aflow diversion member proximal to the fluid outlet, the flow diversionmember configured to block a direct flow between the fluid inlet and thefluid outlet; a membrane comprising a wall separating the liquid chamberfrom an outer chamber, the membrane configured to allow a gas to passfrom the liquid chamber to the outer chamber, wherein the outer chamberis concentrically disposed around the liquid chamber from the fluidinlet to the fluid outlet; and a gas venting valve fluidically couplingthe outer chamber with an atmosphere, wherein the flow diversion memberis mechanically supported by an elongate member extending along a flowdirection into the liquid chamber.
 2. The apparatus of claim 1, whereinthe flow diversion member comprises an ellipsoidal shape longitudinallydisposed along the flow direction.
 3. The apparatus of claim 1, whereinthe flow diversion member comprises an umbrella shape having a convexportion disposed towards the fluid inlet.
 4. The apparatus of claim 1,wherein the flow diversion member comprises a conical shape having anapex disposed towards the fluid inlet.
 5. The apparatus of claim 1,wherein the flow diversion member comprises a pyramidal shape having anapex disposed towards the fluid inlet.
 6. The apparatus of claim 1,further comprising a support cage in the liquid chamber to providemechanical support to the membrane.
 7. The apparatus of claim 6, furthercomprising a strut connecting the flow diversion member to the supportcage.
 8. The apparatus of claim 7, wherein the strut is a hydrofoilhaving a smooth angle of engagement disposed towards the fluid inlet. 9.The apparatus of claim 7, further comprising a support disposed at anend of the strut, wherein the support connects the strut to the supportcage.
 10. The apparatus of claim 6, wherein the membrane is disposed onan inner face of the support cage, between the liquid chamber and thesupport cage.
 11. The apparatus of claim 6, wherein the membrane isdisposed on an outer face of the support cage, between the support cageand the outer chamber.
 12. The apparatus of claim 1, wherein the outerwall comprises a wall perpendicular to a longitudinal axis of the liquidchamber, the wall configured to be impermeable to the fluid flow and tothe gas.
 13. The apparatus of claim 1, wherein the liquid chambercomprises a cylindrical shape with a longitudinal axis aligned with thefluid inlet and the fluid outlet, and further wherein a cross section ofthe cylindrical shape is tapered up in one of a fluid outlet directionor a fluid inlet direction.
 14. The apparatus of claim 1, wherein theouter wall comprises a wall surrounding the outer chamber, the wallincluding a fence around the gas venting valve, the fence configured toprevent an external object to exert pressure on the valve.
 15. Theapparatus of claim 1, wherein the elongate member is supported by one ofthe fluid inlet or the fluid outlet.
 16. A system, comprising: acontainer including an intravenous liquid; a mechanism to provide apressure to move the intravenous liquid through a fluid line to apatient; and a gas elimination apparatus fluidically coupled with thefluid line, and configured to remove gas bubbles from the intravenousliquid, wherein the gas elimination apparatus comprises: a flowdiversion member configured to block a direct flow between a fluid inletand a fluid outlet, the flow diversion member supported by at least oneelongated member extending along a flow direction into a fluid chamber;a membrane comprising a wall separating a fluid from an outer chamber,and configured to allow a gas to pass through from the fluid to theouter chamber; a support cage in the liquid chamber to providemechanical support to the membrane; a strut connecting the flowdiversion member to the support cage; and a gas venting valvefluidically coupling the outer chamber and an atmosphere.
 17. The systemof claim 16, wherein the strut is a hydrofoil having a smooth angle ofengagement disposed towards the fluid inlet.
 18. The system of claim 16,further comprising a support disposed at an end of the strut, whereinthe support connects the strut to the support cage.
 19. The system ofclaim 16, wherein the flow diversion member in the gas eliminationapparatus is selected from the group consisting of an ellipsoidal shapelongitudinally disposed along the flow direction, an umbrella shapehaving a convex portion disposed towards the fluid inlet, a conicalshape having an apex disposed towards the fluid inlet, and a pyramidalshape having an apex disposed towards the fluid inlet.
 20. The system ofclaim 16, wherein the mechanism to provide a pressure comprises one of apump, or a frame to place the container at a higher elevation relativeto the patient.